High pressure forming press

ABSTRACT

An apparatus and method for forming sheet metal. A head platen having a rubber insert and a lower piston casing which accommodates a piston having an anvil adapted to be aligned with the rubber insert are held together by a lock ring. A hydraulic actuation system comprised of a plurality of pistons mounted on the head platen and the piston mounting the anvil operate to impose a concentrated force to press a workpiece mounted on the anvil into the rubber insert.

United States Patent Rasmussen 1451 Aug. 8, 1972 [54] HIGH PRESSUREFORMING PRESS 3,391,559 7/1968 Myers ..72/63 [72] Inventor: AageRasmussen, Stony BlOOk, N.Y. FOREIGN PATENTS OR APPLICATIONS [731Assigmra Grumman Aerospace Corporation, 871,251 6/1961 Great Britain..72/63 Bethpege, 1,167,094 11/1966 Great Britain ..72 57 22 F1 d: Oct.15, 1970 1 16 Primary Examiner-R1chard J. Herbst [21] Appl. No.: 80,911Attorney-Morgan, Finnegan, Durham & Pine [52] US. Cl ..72/57, 72/60 [57]ABSTRACT [51] Int. Cl. ..B21d 22/10 An apparatus and method for formingsheet metal. A [58] Field of Search .;...72/54, 57,60, 63 head platenhavi g a rubber insert and a lower piston casing which accommodates apiston having an anvil 5 References Cited adapted to be aligned with therubber insert are held together by a lock ring. A hydraulic actuationsystem UNITED STATES PATENTS comprised of a plurality of pistons mountedon the head platen and the piston mounting the anvil operate to impose aconcentrated force to press a workpiece 3,264,854 8/1966 Carlisle..72/63 mmmted the rubber msen' 3,290,919 12/ 1966 Malinak et a1 ..72/635 Claims, 5 Drawing Figures PATENTEB I 3.681.958

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' snwsurs 446E fins-Moss? 1 HIGH PRESSURE FORMING PRESS FIELD OF THEINVENTION The invention relates to sheet metal forming presses. Moreparticularly, the invention is directed to a hydraulic flexible diepress for forming sheet metal under extremely high pressures.

BACKGROUND OF THE INVENTION very high working pressures are largeheavily built machines. Basically, the prior art high pressure hydraulicflexible die sheet metal sheet presses employ either an hydraulicallyexpansible container or a solid rubber insert to deform the sheet metalworkpiece around a form or a die.

The hydraulic flexible die sheet metal presses having hydraulicallyexpansible containers are limited in the amount of pressure which theycan exert on the workpiece since the hydraulic fluid transmits the forcein all directions equally rather than directing the force primarily tothe workpiece. Hence, the force on the workpiece will not be greaterthan the pressure on any other part of the hydraulically expansiblecontainers. In addition, large structures must be built around thehydraulically expansible containers to react the pressures therein.

In the case of hydraulic presses having solid rubber inserts fordeforming a workpiece around a form or die, the prior art lacks a pressdesign capable of generating large forces in a small compact apparatus.

2. Summary of the Invention It is an object of the present invention toprovide a hydraulic rubber die sheet metal press of a small, compactsize that is capable of forming parts that would conventionally requirethe use of a large, heavy-duty press.

To this end, a hydraulic forming press is provided having an upper headplaten, a base piston casing, a lock ring and a hydraulic system.

The upper head platen is formed with a centrally disposed cavity intowhich a rubber insert is fitted. The base piston casing accommodates asingle large piston on which an anvil is mounted. The upper head platenand the base piston casing are arranged such that the anvil and rubberinsert are in vertical alignment. Both the head platen and base casinghave outer flanges of the same diameter.

The lock ring is formed of two virtually identical halves which aremounted for translation into and out of the operative position. Each ofthe lock ring halves have formed therein an internal recess having aheight substantially the same as the combined height of both the headplaten flange and the base piston casing flange. In the operativeposition, the lock ring halves are translated into abutting relationshipwherein the internal recesses thereof conform to the flanges of the headplaten and base casing.

The press hydraulic system includes a plurality of hydraulic pistoncylinders mounted on the head platen. The piston rods of the pistoncylinders transpierce the head platen and are fixedly secured in thebase piston. Thus, by introducing pressurized fluid into the pistonchambers on the side of the lower piston face, the head platen isforcibly lowered into the operative position. The hydraulic system alsoincludes means for introducing pressurized fluid into the bottom of thebase casing to force the base piston upwardly.

Operationally, a workpiece or a die is first placed on the anvil. Next,fluid under pressure is introduced into the bottom of the pistoncylinders on the platen head to operate against the lower faces of thepistons. As a consequence, the head platen is lowered thereby forcingthe rubber insert against the anvil to initially deform the workpiece.After a pressure equilibrium condition is reached, the lock ring ismoved into engagement with the flanges on the base casing and the headplaten. Next, fluid under pressure is pumped into the base casing pistonchamber to drive the piston upwardly thereby forcing the workpiece andthe die further into the rubber insert. The relatively large area of thepiston 0 surface on which the fluid is operating in comparison toDESCRIPTION OF THE DRAWINGS The present invention and the attendantadvantages will become better understood as explained with reference tothe accompanying drawings wherein:

FIG. 1 is a perspective view of the hydraulic press constituting thepresent invention;

FIG. 2 is an elevational view, partly in section, of the hydraulic pressshown in FIG. 1;

FIG. 3 is a sectional plan view of the hydraulic press through line 3-3of FIG. 2;

FIG. 4 is a partial sectional elevational view of one of the hydraulicpiston cylinders on the platen head; and

FIG. 5 is a simplified hydraulic control system for the hydraulic press.

DESCRIPTION OF THE PREFERRED EMBODIMENT The press 2 of the presentinvention is shown in FIG.

1 in the inoperative open position.

The press 2 is mounted on a pedestal 4 and is comprised of a base casing6, a head platen 8 and a lock ring 10 having complementary mating clampmembers 12 and 14 which retain the head platen 8 in contact with thebase casing 6 and react the force imposed thereon during the formingoperation. The press 2 is also provided with an initial hydraulicactuation assembly 16 which consists of hydraulic actuation cylinders18, 20, 22, 24 (best seen in FIG. 3).

As best seen in FIG. 2, the base casing 6 is formed with an innerchamber 25, an outer flange 26 and a centrally disposed fluid passage28. The inner chamber 25 is sized to slidably accommodate a piston 30.Annular recesses 32 and 34 are formed in the surface of the piston 30for rings 36 and 38. The rings 36 and 38 surround the piston 30 andenhance wear and alignment thereof. A base plate 40 is attached to thepiston 30 by any suitable means,such as bolts 42. The base plate 40 isconfigured with a central cavity 44 to facilitate the entry of actuationfluid into chamber 25.

An annular seal 46 is arranged around the periphery of the piston 30 toprevent the escape of hydraulic actuation fluid. In practice it has beenfound that an elastomeric seal or a plurality of V-shaped elastomericseals in tandem located in proximity to the base plate 40 isparticularly suitable.

The outer flange 26, shown in FIG. 2, is integrally formed with the basecasing 6. The flange 26 is configured to fit within the lock ring suchthat the lower surface 48 of flange 26 provides a surface for the lockring 10 to grip.

The centrally disposed fluid passage 28 extends from the piston chamberto the exterior of the base casing 6 to afford communication between thepiston chamber 25 and a fluid source under pressure. As seen in FIG. 2,high pressure fluid hose 50 from a pressurized fluid source 54 isconnected to the fluid passage 28 by fluid coupling 52.

Mounted on the center of the piston upper surface 56 is an anvil 58,seen in FIGS. 1 and 2, which rests on an anvil support 60, seen in FIG.2. In practice it has been found that the anvil support should befixedly attached to the piston upper surface 56 by a known bolt anddowel arrangement and the anvil 58 mounted on the anvil support 60 by afurther bolt and dowel arrangement. The elevation of the upper surface62 of the anvil 58 is slightly above the elevation of the upper surface64 of the base casing 6. The anvil 58 is the surface on which theworkpieces to be formed by the press 2 are placed.

The head platen 8, best seen in FIG. 2, is sized to mate with the basecasing 6 and, hence is similarly configured. The headplaten 8 is formedwith a centrally disposed cavity 66, best seen in FIG. 2, four throughgoing holes 68, 70, 72, 74, best seen in FIG. 3, and an outer flange 76.

The centrally disposed cavity 66 is formed with a shoulder 67 and filledwith a hard rubber insert 78. A variety of rubber inserts can be used,depending on the particular application, however, in practice, about aneighty durometer rubber insert is particularly satisfactory for formingsmall airplane parts.

= The outer flange 76 on the head platen 8 is formed with the same outerdiameter as the flange 26 on the base casing. Together the flanges 76and 26 provide the surfaces which the lock ring 10 grips to retain thebase casing 6 and the head platen together during the press formingoperation.

The initial hydraulic actuator assembly 16, seen in FIGS. 2, 3 and 4, iscomprised of four actuator piston cylinders 18, 20, 22, 24 having pistonrods 88, 90, 92, 94 and pistons 80. Each piston cylinder 18', 20, 22, 24is fixedly mounted on the upper surface of the head platen 8 over arespective through-going hole 68, 70, 72, 74. The piston rod 88, 90, 92,94 associated with each cylinder 18, 20, 22, 24 extends through thethrough-going holes 68, 70, 72, 74 over which the respective cylinder ismounted and are fixedly attached to the piston of the base casing 26.However, the piston rods 88, 90, 92, 94 are slidably arranged in thethrough-going holes 68-74 to allow the head platen 8 to moveuninhibitedly. Any means can be used to secure the piston rods 88-94 tothe piston 30, such as threaded holes 96 in the piston 30 adapted to fitthe threaded ends 104 of the piston rods 88-94, as best seen in FIG. 4.Movement of the head platen 8 is effected by fluid in the cylinders 18,20,22, 24 acting on either of the respective faces of the pistons 80. Iffluid I downwardly.

The lockring 10, seen in FIGS. 1, 2 and 3, is designed to grip the headplaten flange 76 and the base casing flange 26 during the formingoperation. Each of the complementary mating clamp members 12 and 14 issemi-circular in planform and each is formed with an inner recess 112into which the flanges 76 and 26 can fit; The clamp members 12 and 14are slidably mounted on rails 114, 116, 118, 120, seen in FIG. 3.Rollers 122, best seen in FIG. 2, depend from the clamp members 12 and14 and insure the alignment of the clamp members 12 and 14 as theytravel on the rails 114-120. Actuators, such as fluid actuators 124, areadapted to move the clamp members 12 and 14. The actuator rods 126 ofthe actuators 124 connect directly to each respective clamp member 12and 14.

A schematic of a system for controlling the machine function of thepress 2 is shown in FIG. 5. The system depicted is the simplestoperative form and does not include any of the system safety devicessuch as hydraulic fuses which are necessary for practical operation. Ahigh pressure pump 130 and a low pressure pump 132 are connected with afluid source 134. It should be noted that independent fluid sourcescould be provided. Pump 130 supplies the high pressure fluid for thefluid hose 50 which delivers the fluid to the piston chamber 25 in thebase casing 6. A- valve 131 in the hose 50 is provided to affordselective communication between the piston casing 25 and either the pump130 or the system sump.

The low pressure pump 132 delivers fluid to both the initial hydraulicactuators 18, 20, 22, 24 of assembly 16 and the actuator cylinders 124which control the lock ring 10. The line 136 from the pump 132 connectswith branched lines 138 and 140 which extend to the initial hydraulicactuator assembly 16 and the lock ring actuator cylinders 124respectively. Valves 142 and 144 are provided for lines 138 and 140respectively to afiord selective communication between the pistonchambers and either the pump 132 or the system sump.

In operation, the hydraulic press 2 is first loaded either manually orautomatically by setting a workpiece and die or the anvil 58, as seen inFIGS. 1 or 2. Next, the hydraulic system is engaged by providingcommunication between the low pressure pump 132 and the bottom of eachof the initial hydraulic actuators 18, 20, 22 and 24. As the fluidenters'the bottom of the initial hydraulic actuators 18, 20, 22 and 24,the head platen 8 is forced downwardly since the piston rods 88, bestseen in FIG. 4, are fixedly secured to the piston 30. The workpiece anddie are forced into the rubber insert 78 until a pressure equilibrium isreached. At or near the point wherein the flange 76 is below the top ofthe recess 112 in the lock ring 10, a signal is sent by any suitableconventional means to valve 144 to provide communication between thehydraulic actuators 124 and the low pressure pump 132. The force of thefluid on the outside face of the pistons of cylinders 124 forces thelock ring halves l2 and 14 into the operative position wherein therecess 112 in the lock ring assembly 10 surrounds and grips the basecasing flange 26 and the head platen flange 76.

the head platen 8 to the base casing 6, a signal is sent to valve 131 toprovide communication between the high pressure pump 130 and the pistonchamber 25. Again, any conventional signal or relay means can be used toregulate the valves 131. Fluid from the high pressure pump 131 is thenintroduced into piston chamber 25 to force the piston 30 upwardly and,as a consequence, drive the workpiece and die further into the rubberinsert 78. The upward motion of the piston 30 acts to force the pistonin the initial hydraulic actuation cylinders 18, 20, 22 and 24 furtherupwardly, hence both the initial and final hydraulic actuation systemsare operating with each other rather than against each other. Since thearea of the face of the piston 30 is large in comparison to the area ofthe anvil, the composite force of the hydraulic fluid operating on thepiston face will be transferred to the smaller area anvil.

In practice it has been found that an anvil 58 having a surface area 250square inches and a piston 30 having a surface area of 1,000 squareinches will provide a design which delivers a force to the rubber insert78 four times the hydraulic force at the lower face of the a verticallymovable piston in the base piston V chamber;

an anvil on the vertically movable piston for supporting a workpiece anddie;

an outer peripheral flange at the top of the base piston chamber;

a vertically movable head platen having a centrally disposed cavity;

elastic means in the cavity for pressing the workpiece against the dieto conform the configuration of the workpiece to the die configuration;

an outer peripheral flange on the bottom of the head platen;

a plurality of hydraulic piston actuators, the cylinders of which arefixedly mounted on the head platen and the piston rods of which slidablytranspierce the head platen and are fixedly secured to the piston in thebase casing;

means for selectively introducing hydraulic fluid into said pistoncylinders on either side of the piston to thereby raise and lower thehead platen whereby lowering the head platen to contact the verticalpiston produces an initial force for pressing the workpiece and die intothe means in the cavity; and

means for producing a final force of a greater magnitude than theinitial force for further pressing the workpiece and die into theelastic means.

2.A press for forming sheet metal parts comprising:

a vertically movable piston in the v base piston h be an anvi ori thevertically movable piston for supporting a workpiece and die;

an outer peripheral flange at the top of 'the base piston chamber;

a vertically movable head platen having a centrally disposed cavity;

elastic means in the cavity for pressing the workpiece against the dieto conform the configuration of the workpiece to the die configuration;

an outer peripheral flange on the bottom of the head platen;

a first hydraulic system comprising a plurality of hydraulic pistonactuators, the cylinders of which are fixedly mounted on the head platenand the piston rods of which slidably transpierce the head platen andare fixedly secured to the piston in the base casing;

means for selectively introducing hydraulic fluid into the firsthydraulic system piston cylinders on either side of the piston tothereby raise and lower the head platen;

whereby lowering the head platen to contact the vertical piston producesan initial force for pressing the workpiece and die into the means inthe cavity; and

a second hydraulic system for moving the vertically movable piston inthe base piston chamber for producing a final force of a greatermagnitude than the initial force for further pressing the workpiece anddie into the elastic means.

3. A press as in claim 2 wherein the lock ring is comprised of matinghalf rings and further comprising means to mount the lock ring halvesfor translation into and out of engagement with the flanges of the headplaten and the base casing and a third hydraulic system to translate thelock rings halves on the mounting means. i

4. A press as in claim 3 further comprising a source of low pressurehydraulic fluid for the first and third hydraulic systems and a sourceof high pressure hydraulic fluid for the second hydraulic system.

5. A press as in claim 4 wherein the surface area of the anvil isone-quarter times the bottom surface area of the piston mounting theanvil.

2353? I 6FF'iCE CERTIFICATE OF CORRECTION Patent No. 3,681,958 DatedAugust 8, 1972 Inventor(s) Aage Ra smus sen It is certified that errorappears in the above-identified pat ent and that said Letters Patent arehereby corrected as shown below:

In claim 2, after "comprisingz" add the element a base piston chamber;

Signed and sealed this 20th day of February 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOI'TSCHALK A'ttestlng Officer Commissionerof Patents

1. A press for forming sheet metal parts comprising: a base pistoncHamber; a vertically movable piston in the base piston chamber; ananvil on the vertically movable piston for supporting a workpiece anddie; an outer peripheral flange at the top of the base piston chamber; avertically movable head platen having a centrally disposed cavity;elastic means in the cavity for pressing the workpiece against the dieto conform the configuration of the workpiece to the die configuration;an outer peripheral flange on the bottom of the head platen; a pluralityof hydraulic piston actuators, the cylinders of which are fixedlymounted on the head platen and the piston rods of which slidablytranspierce the head platen and are fixedly secured to the piston in thebase casing; means for selectively introducing hydraulic fluid into saidpiston cylinders on either side of the piston to thereby raise and lowerthe head platen whereby lowering the head platen to contact the verticalpiston produces an initial force for pressing the workpiece and die intothe means in the cavity; and means for producing a final force of agreater magnitude than the initial force for further pressing theworkpiece and die into the elastic means.
 3. A press as in claim 2wherein the lock ring is comprised of mating half rings and furthercomprising means to mount the lock ring halves for translation into andout of engagement with the flanges of the head platen and the basecasing and a third hydraulic system to translate the lock rings halveson the mounting means.
 4. A press as in claim 3 further comprising asource of low pressure hydraulic fluid for the first and third hydraulicsystems and a source of high pressure hydraulic fluid for the secondhydraulic system.
 5. A press as in claim 4 wherein the surface area ofthe anvil is one-quarter times the bottom surface area of the pistonmounting the anvil.